I'm new to Debian. And I'm sorry if I've done something wrong. I thought that what I have written is about "Grub doesn't see Windows". This is my 6th comment, and I'm learning from the others how the text should be. I thought that what I have written was ok. I want to stay here, but if you still want me to leave, I will do it.

Anyway, the Debian system is already booting so their grub.cfg is fine (apart from the missing Windows entry).

The OP's Debian installation is almost certainly booting in non-UEFI mode (hence the absence of an entry for the UEFI Windows system), a quick check for /sys/firmware/efi will confirm this for sure, as I already stated in my first post in this thread.

_nobody_ wrote:The 5th is one of the tries (first one) to restore correct grub.cfg

I'm curious: why change directory to /boot when grub-mkconfig is given a full path for the output? Are you really that stupid?

@jibberjabberSome people (like me), use Windows and plan to move slowly to Linux, but as a not experienced Linux user I need Windows for some time to be able to use old programs. When I feel confident about Linux, know more, install all necessary programs then I will use Debian more often. It takes time.

regees wrote:@jibberjabberSome people (like me), use Windows and plan to move slowly to Linux, but as a not experienced Linux user I need Windows for some time to be able to use old programs. When I feel confident about Linux, know more, install all necessary programs then I will use Debian more often. It takes time.

Yes it takes time. I think dual boot is maybe something you should research a little, instead of jumping right into it. What I did was use a live system for a few months, before even installing, I was that scared of linux. By practicing with a live usb/cd/dvd you can get used to the terminal and learn about the system before trying to tackle tougher issues that you're not familiar with. You can experiment a lot without damaging your working windows system.

There are a lot of threads available, but since UEFI has come along, they aren't always relevant. It's now even more complicated to setup a dual boot machine. I'm not sure I'd do it anymore at all...

Take your time, pardon the noise, and hang in there, it's worth it in the long run.

Problem solved in my case.It was enough to disable CSM (Compatibility Support Mode) in UEFI and reinstall Debian.I didn't do anything with Windows 10, left it as it is, as I found that it uses UEFI and GPT already (despite CSM).

Glad to hear you solved it, later you may want to consider some other alternatives as well, ===below====

There are a lot of threads available, but since UEFI has come along, they aren't always relevant. It's now even more complicated to setup a dual boot machine. I'm not sure I'd do it anymore at all...

This is a good point, and even though it does not solve the "Grub doesn't see Windows"problem, so maybe should be another topic. But the OP said in their first post and also here:

regees wrote:@jibberjabberSome people (like me), use Windows and plan to move slowly to Linux, but as a not experienced Linux user I need Windows for some time to be able to use old programs. When I feel confident about Linux, know more, install all necessary programs then I will use Debian more often. It takes time.

Being new to all of this, maybe they are not aware of some other options, so any way, here we go, please bear with me, this may get kind of long.

What I would do is use a virtual machine , and Debian, or any other Linux distro as a guest on a VM , later if and when you are more comfortable with Linux, and if you want to use it, then install it as the main OS. Using multi-boot set-ups, used to be almost the only option, but now that virtualization and Virtual Machines are much more advanced and work very, (actually since I am not a MS windows user, I am not sure if they have any good VM software or not, I would think they do),

but since UEFI has come along, they aren't always relevant. It's now even more complicated to setup a dual boot machine.

The biggest drawback to dual boot:Let's say you have booted with Linux, and you are doing some studying, learning more about , etc,... or what ever, but something comes up, and you need to use a program that you have on the Windows partition. You can not just boot the windows partition, just like that, you will need to shutdown the linux system, completely , and be sure to save all your work, before shutting down. Then re-boot, selecting the windows system, if and when you get grub working properly.Re-booting to MS windows will take some time, the few times I did try using windows, this was one of the biggest complaints I had, it is sooo slooowww, to boot. Ok , so then you do what ever you needed to do on the windows partition, now you want to use Linux ,and return to what you were doing there,...the whole same process again, save everything and shut down, Then boot with the Linux system,... It gets to be a royal pain in the butt, trying to use 2 different OS's and having to re boot every time you want to use the other. Just plain stupid, in my opinion. With a VM, you can start the VM, play around with your Linux system, but if and when you need to do something using the windows program, no need to shut everything down and reboot, just minimize or put the window for the VM in the background, do what you need to do, when you finish, 1 click restores the VM window, and your back on your Linux. If you have the resources $$$, really, it is better to have 2 computers, 1 dedicated to Linux, the other to Windows, ... no need to be rebooting every time you need run something that is on the other system, both PC's or laptops can be running and booted all the time. Using a multi boot system is the last choice I would make now a days. Everything is so much easier now a days , with the excellent Virtualization technology. So any way, guess that is about it,..

regees wrote:Problem solved in my case.It was enough to disable CSM (Compatibility Support Mode) in UEFI and reinstall Debian.I didn't do anything with Windows 10, left it as it is, as I found that it uses UEFI and GPT already (despite CSM).

I would like to thank you, for reading my posts/taking my advises. It shows something... I tried here just to do pure help, and I do NOT have big EGO. Just trying to help! Sometimes I am clumsy... _nobody_ is perfect!

GarryRicketson wrote:it does not solve the "Grub doesn't see Windows" problem

The OP has solved their problem by following the advice I gave in my first post in this thread, everything else has been noise.

I am sure H_O_A_S appreciates the thank you, and so do I , so your welcome, even though my post was just noise, I apologize for that, oh and on this:

But some people do NOT understand... Not at all.

Don't worry, "be happy", it does not matter what other people , or "some people" think, or do not understand, as long as you understand, that is what counts, I have my own way of doing things, and I understand it, it works for me, so WHY worry about if others understand it or not, ?

Oh, and Grub does not see windows on my system either, but I all ways thought that was good, and never though of it as a problem, guess I just don't understand, but it does not matter, I am happy.

Don't worry, "be happy", it does not matter what other people , or "some people" think, or do not understand, as long as you understand, that is what counts, I have my own way of doing things, and I understand it, it works for me, so WHY worry about if others understand it or not, ?

Hello Garry,

BSP (Board Support Package) per say, is very complicated. The whole thing is the best to compare to the rocket, with several stages/phases of flight until the command capsule reaches the Earth's Orbit. For the Client PC, the first notification is BIOS/UEFI, then OSes' boot-loader (for WIN10 it is WIN boot-loader, for most Linux distros usually GRUB 2.0x). And after passing GRUB, there is a Dracut phase, then sbin/init (init process) phase (run level 1, single user)... Until Linux reaches run level 5 (GFX multi-user) stage.

As you see, many levels, and for each level you have to know at least something about it, to intervene and fix the issues.

As I use Debian last 12+ months, exclusively for embedded platforms and as VBox VMs, I am learning lot of differences between Fedora and Debian itself. And, there are plenty of differences, as I do dive deeper into Debian...